Cars, on being subject to vibration, produce noises that disturb the occupants of the vehicle. Some of these noises are produced by the cables on knocking against the vehicle bodywork as a result of said vibrations. The vibrations also cause wear to the cables and, consequently, of the protective tube.
In order to prevent these nuisances for some time protective tubes have been used that cover the vehicle cables and absorb the noise.
These protective tubes are made from braided threads of plastic materials, which have the advantage of being very elastic and of adapting to different cable diameters. In order to provide the protective tube with the characteristics necessary to absorb the noise, these tubes also include threads of a texturised material.
In patent ES-A-2.210.854, belonging to the same owner as this present application, an insulating tube is described that is formed from different types of threads that allow the combination of elasticity and noise absorption, in addition to resistance to abrasion and temperature.
Due to the increase of cabling in cars, resulting from the ever increasing incorporation of electrical and/or electronic equipment, the applicant has come up against the problem that until this time was unknown, this being the limited diameter of said protective tubes.
The applicant has come to the conclusion that if protective tubes could be made with a greater diameter more cable could be passed through each tube, making the assembly of the vehicle electrics easier. However, with the current manufacturing machines the manufacture of protective tubes with a greater diameter is not viable.
This impossibility is due to the fact that current machines have a circular head fitted with a plurality of needles. This head is surrounded by thread guides that feed a thread to each needle. From this machine it is clear that there is a space limitation for the amount of threads that are necessary to make tubes with a greater diameter. In addition this machine is specially designed for the manufacture of protective tubes with small diameters, as it was considered to be the most suitable solution up to the present time.
On the other hand, the warp knitting machines, such as the Raschel type knitting machines have been known for some time, but their field of application is usually a long way from the car industry.
For example, U.S. Pat. No. 4,784,886 describes a knitted fabric made on a flat bed machine with laying of the yarn. However, in said document, no procedure is described for the manufacture of said fabric.
Patents U.S. Pat. No. 5,413,149, U.S. Pat. No. 5,556,495, EP 0425 099 and WO97/32067 describe flat or open fretwork fabrics, and also make reference to a shaping process. However, at no time do they describe the use of a Raschel loom.